With few exceptions, all of the existing versions of the magnetic flowmeters measure the amplitude of an electromotive force resulting from the dynamic electromagnetic interaction between the moving electrically conductive fluid and an alternating magnetic field, and determine the velocity of the fluid as a function of the measured amplitude of the electromotive force. Generally, the electromotive force generated by the dynamic electromagnetic interaction between the moving electrically conductive fluid and the alternating magnetic field includes the noise signal such as the electromotive force generated by the static electromagnetic induction from the alternating magnetic field and other ambient electromagnetic fields, and consequently, it requires a complex and expensive electronic conditioning of the electrical signal under the amplitude measurement before determining the fluid velocity from the amplitude of the electromotive force. An earlier invention made by these inventors disclosed in a patent application "Phase Detection Method for Flowmeters and Other Applications" teaches a method that determines the velocity of an electrically conductive fluid moving transversely across an alternating magnetic field as a function of phase angle difference between two alternating electrical signals generated by the dynamic electromagnetic interaction between the moving electrically conductive fluid and the alternating magnetic field and by the static electromagnetic induction from the alternating magnetic field, wherein the noise signals included in the two alternating electrical signals become excluded when the phase angle difference between the two alternating electrical signals is taken as a measure of the velocity of the electrically conductive fluid. The present invention discloses the generalized version of the method for and universal principles of operating a magnetic flowmeter that determines the velocity of an electrically conductive fluid as a fuction of phase angle difference between two alternating electrical signals generated by the dynamic and static electromagnetic inductions, and the construction of the magnetic flowmeters that execute the method of phase angle difference in measuring the velocity or volume flow rate of an electrically conductive fluid. In conclusion, the present invention provides a new generation magnetic flowmeter that measures the flow rate of electrically conductive fluids with a much greater accuracy and. reliability, and yet costs much less compared with the existing versions of the magnetic flowmeters.